Let
x ----> the first consecutive integer number
x+1 ---> the second consecutive integer number
x+2 ---> the third consecutive integer number
so
we have that
x+(x+1)+(x+2)=261
solve for x
3x+3=261
3x=258
x=86
therefore
x=86
x+1=87
x+2=88
The numbers are 86,87 and 88